1. Field of the Invention
The present invention relates to a semiconductor device having a configuration for heat radiation from a semiconductor chip to a casing. The present invention also relates to a method for manufacturing such a semiconductor device.
2. Description of Related Art
There is known a semiconductor device that has a face-down mounting structure. In a typical face-down mounting structure, an electrode is located on one surface of a semiconductor chip, and is electrically connected to a wiring pattern of a board with the one surface of the semiconductor chip being directed to the board. For improvement of heat radiation efficiency from a semiconductor chip having a face-down mounting structure, a heat sink made of metal or the like is connected to another surface of the semiconductor chip, wherein the another surface is opposite to the one surface where the electrode is located (cf. U.S. Pat. No. 6,873,043).
Discussion is presented below on the above semiconductor device, as a related art. Heat radiation efficiency may improve by contacting a heat sink with a semiconductor chip or a casing that receives a board. However, since the heat sink and the casing are typically made of metal, the contact between the casing and the heat sink leads to a state where the heat sink and the casing are electrically connected. In such a case, there may generate a leak between a back side of the semiconductor chip and the casing. It is thus necessary to place an insulating layer between the heat sink and the casing to prevent the direct contacting. For example, an insulating layer may be formed on a portion of the casing that is supposed to face the heat sink. Alternatively, an insulating film may be placed between the casing and the heat sink when the semiconductor chip and the heat sink are fixed to the casing. However, when the insulating layer is formed on the casing, it is required to form insulating layers on all casings one by one. Thus, a process of forming the insulating layer becomes complicated. When an insulating film is placed between the heat sink and the casing, it is required to place the insulating film every time when the semiconductor chip and the heat sink are fixed to the casing, which results in a complicated process.